flavincontaining

Flavin-containing is an adjective used to describe molecules, enzymes, and proteins that include a flavin moiety as part of their structure or function. The term most often refers to flavin cofactors derived from riboflavin (vitamin B2): flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). Flavin-containing species participate in redox reactions, cycling between oxidized, semiquinone, and reduced forms.

In biology, many enzymes are flavoproteins, employing FAD or FMN to catalyze oxidation and reduction steps in metabolism, respiration, and detoxification. The flavin cofactor is typically bound tightly as a prosthetic group, though in some cases it binds reversibly. Its ability to undergo one- and two-electron transfers, along with stabilization of radical intermediates, enables diverse chemistry. Examples include succinate dehydrogenase (FAD), various oxidases and dehydrogenases (FMN or FAD), and flavin-containing monooxygenases that incorporate oxygen into substrates.

Biosynthesis and function: organisms obtain riboflavin from diet or synthesize it, and riboflavin is converted to FMN by riboflavin kinase and to FAD by FAD synthetase. The flavin cofactor participates in catalytic cycles and can generate reactive oxygen species when misregulated.

Applications and significance: flavin-containing compounds and enzymes are used as biocatalysts, in biosensors, and as photosensitizers in photoredox catalysis. The term is commonly encountered in discussions of enzyme families, such as flavoproteins and flavin-containing monooxygenases.